(NBC News) -- In its most aggressive decision yet in applying federal benefits to same-sex couples, the Obama administration has concluded that legally married same-sex couples are entitled to military veteran's benefits.

It's the latest move by the administration following the Supreme Court decision in late June that struck down the federal Defense of Marriage Act.

The Department of Veterans Affairs says it's trying to determine the scope of the decision -- how many couples and which benefits this would cover -- but presumably it's the full range of benefits.

What's unusual about this move is that it's a directive to stop enforcing two provisions of federal law that blocked same-sex couples from receiving VA benefits. So far, the government's decisions about which benefits should apply to same-sex couples have been based on interpreting federal rules, not laws.

A letter to congressional leaders from Attorney General Eric Holder says President Barack Obama has directed the VA to stop enforcing two federal laws that define a surviving spouse as "a person of the opposite sex who was the spouse of a veteran." Those provisions govern who's eligible for benefits provided to veterans and their families, and in some cases also to active duty or reserve members and their spouses.

As Holder's letter notes, decisions to stop enforcing a federal law "are appropriately rare." But he says this action is based on the wording of the DOMA ruling, which said it's unconstitutional to treat legal same-sex unions as second-tier marriages. The provisions of law governing VA benefits, he says, are virtually the same as the parts of DOMA that were struck down.

Holder also says a federal judge in California reached a similar conclusion last week.

"Continued enforcement would likely have tangible adverse effects on the families of veterans and, in some circumstances, active-duty service members and reservists, with respect to survival, health care, home loan, and other benefits," Holder says in his letter to the Hill.